The invention relates to encoding block-organized audio/video data.
The processing of digital audio and video, such as for transmission or for storage, has necessitated the use of various data compression technologies. A non-limiting example is the MPEG standard, that has various versions for audio as well as for video. Another standard is H.261. Realizing such compression in software has been disclosed in Ho-Chao Huang et al, New Generation of Real-Time Software-Based Video Codec: Popular Video Coder II, IEEE TR. Cons.El. Vol.42, No.4, P.963-973. It is feasible to have compression and similar operations executed in a mixed software and hardware environment. The number of operations necessary for software encoding is difficult to predict. An embodiment hereinafter will be mainly described with reference to video. Now, generally the compression is executed on the basis of Groups of Pictures (GOPs). Hereinafter, the term xe2x80x9cpicturexe2x80x9d will be used consistently. Depending on the actual video standard, the term xe2x80x9cpicturexe2x80x9d may mean xe2x80x9cframexe2x80x9d as well as xe2x80x9cfieldxe2x80x9d. Now, the compression of framewise organized audio or mixed audio/video information streams may be effected in similar manner. Such processing must be done in real-time, and a high penalty must be paid in case of processor overload, by loosing pictures or parts thereof. Graceful degradation has been widely used in data processing, by surrendering a certain degree of quality in order to preserve basic system facilities.
In consequence, amongst other things, it is an object of the present invention to provide an improved encoding method. Now therefore, according to one of its aspects the invention is characterized as recited in the characterizing part of Claim 1. The invention also relates to an encoder device arranged for implementing the above method. Further advantageous aspects of the invention are recited in dependent Claims.
The inventors have recognized the potential value of various control parameters that are defined over a picture or a part of a picture, such as a slice, for controlling the actual processing load. A suitable parameter for video is a redundancy quantity Q that indicates an amount of information to be treated as inconsequential within a block or within an overall picture. According to a primary aspect of the invention, an actual processing load is used to predict future processing load, and in consequence, to adjust one or more control parameters for avoiding overload-inflicted losses of information.
These and further aspects and advantages of the invention will be discussed more in detail hereinafter with reference to the disclosure of preferred embodiments.